1. Field of the Invention
The present invention relates to an imaging apparatus capable of viewing a subject by selecting either a first finder mode for optical viewing of the subject image or a second finder mode for electronic viewing of the subject image acquired by an image pickup device and displayed on a display unit.
2. Description of the Related Art
There is known an imaging apparatus (electronic camera) so-called digital camera having two finder modes: one is a mode for viewing of a subject image through an optical finder including an optical member such as a pentaprism or Porro prism, and the other is a mode for electronic viewing of a subject image through a live view display in such a manner that image data acquired by an image pickup device such as a CCD image sensor or a CMOS image sensor is displayed on a image display unit such as an LCD device as the live view display (through image display). The latter finder mode is referred to as an electronic viewfinder (EVF).
An electronic camera provided with these two finder modes is disclosed, for example, in Japanese Patent Application Laid-Open No. 2000-333064.
In the meantime, in case of use of an electronic viewfinder in an imaging apparatus provided with an optical finder and the electronic viewfinder, the temperature of an image pickup device such as a CCD increases because of continuous driving of the image pickup device. The temperature rise in the image pickup device results in an increase in noise called dark noise or fixed-pattern noise. For this reason, a problem arises that the image quality of the image data acquired is degraded at the time of use of the electronic viewfinder.